Process of dyeing leather with acid azo dyestuffs



Patented Nov. 6, 1928.

V UNITED STATES BARTHOLOMKUS VOSSEN, OF HOCHST-ON-THE-MAIN, GERMANY,ASSIGNOR TO GRAS- SELI-I DYESTUFF CORPORATION, WARE.

OF. NEW YORK, N. Y., A CORPORATION- OF DELA- PROCESS OF DYEING LEATHERWITH: ACID AZO DYESTUFFS.

No Drawing" IArplication filed January 23, 1926, Serial No. 83,389, andin Germany February 3, 1925.

I have found that deep and full brown dyeings can be produced on leathertanned by any method and this with such a depth of I shade as could htherto not at all be obtained in the art of dyeing leather by means ofacid azo dyestuffs or only by means of mixtures of various dyestuffs ofthis kind, it there are used dyestuffs formed according to the followingscheme:

I II III IV amine-mon-su1fonated-aminonaphtholsu1fonic acid -ami1:resorcinol or naphthylanunsulfonic acid In this scheme the term amine (Iand IV) comprises: a

All diazotizable aromatic amines, aminohydroxy and amino-azo compoundsand also their substitution products including the sulfonic acids andcarboxylic acids, for instance aniline, p-nitraniline, aminoazoben zene,2- chlor-fi-toluidine-4-sulfonic acid, p-nitro-oaminophenol, picramicacid, naphthionic acid, or the like;

The term non-sulfonated resorcinol (II) comprises:

Resorcinol and its substitution products including the carboxylic acidswith the exception of the respective sulfonic acids, for in- 1 stanceresorcinol, chlorresorcinol, 1.3.4-resorcylic acid or the like;

The acids mentioned under III comprise: Aminonaphtholmonoor disulfonicacids as well as naphthyl-aminemonoor disulfonic acid} for instance1-amino 8-hydroxynaphthalene-3.6-disulfonic acid acid), l-amino 8hydroxynaphthalene 4.6 disulfonic acid (K acid),1-amino-8-hydroxynaphthalene-t sulfonic acid, and the technical mix-,,

ture of 1-naphthylamine-6-sulfonic acid and 1-naphthylam'ine-7-sulfonioacid; and the arrow points from the amino compound which is diazotizedto the compound with which the i diazotized amino compound is coupled.

Some of the 'dyestufis of the aforementioned type are already known, butthey were hitherto only described as being suitable for use as acid orchrome mordant dyestuffs for wool. They were, however, not adopted to agreat extent, probably owing to their unsatisfactory levelling power andthe insuflicient fastness of the dyeings obtained therewith on wool.

It could not at all be foreseen that the dyestuffs prepared according tothe foregoing scheme, which are almost of no value for dyeing wool, areeminently suitable for dyeing leather. The dyestulfs belonging to thisclass are particularly distinguished by the beautiful tints they give onleather and they are therefore of great value in the art of leatherdyeing. Moreover they enable the leather-dyers to obtain deep and Y fullbrown tints on leather by means of a single dyestufi' and thus toabandon the use of dyestuff mixtures hitherto'required for obtaining thesaid tints, which mixtures were apt to cause difliculties in the dyeingprocess. The dyestuffs belonging to the said type also possess excellentcovering and levelling properties so much so that not only the grain ofthe leather but also the defective spots on it are dyed even tints ofeven depth. Such even dyeings on leather could not be obtained by thehitherto used dyestulf mixtures, because the various components of suchmixtures are apt to give on the defective spots a tint which differsfrom that of the grain.

The fastness of the dyeings obtainable on leather by the dyestuffs inquestion entirely satisfy the requirements to be made in regard todyeings on leather.

The method of dyeing with the dyestuffs of the above defined compositionis the same used in dyeing with acid azo tion has been continued for 10minutes, there are slowly added 200 cc. of formic acid of strengthdiluted with 2 litres of water, and the operation is continued foranother 20 minutes. Thereupon there is added a fat as usual.

In the same manner maybe dyed barktanned sheepskin-leather andkid-leather with the only exception that in these cases the addition ofa fat may be omitted.

Instead of the dyestufi indicated in the foregoing example there may beused in the same manner for dyeing the leather the folture asaforesaid-- resorcinol naphthionic acid picramic acid technical mixtureas aforesaid-aresorcinole-picramio acid.

I claim:

1. The process of dyeing leather in full brown shades of even depth withacid azo dyestuffs, which comprises using for the dyeing processdyestuffs formed according to the scheme:

I II III IV amino-mon-su!ionatcd aminonaphthol sulfonic wid -aminercsorcinol wherein I and IV each stand for a diazotizable aromaticamine, aminohydroxyor amino-azo compound or a substitution productthereof, II stands for non-sulfonated resorcinol or a substitutionproduct thereof, and III stands for an aminonaphthol monoor disulfonicacid.

2. The process of dyeing leather in full brown shades of even depth withacid azo dyestufi's, which comprises using for the dyeing processdyestuffs formedaccording to the scheme:

I II III IV R-NHznon-sulfonntedinminonaphthol s u 110 111 c -emineresorcinol acid wherein R in I stands for an aromatic nucleus which maycontain an NO group, II stands for non-sulfonated resorcinol or asubstitution product thereof, III stands for an aminonaphthol monoordisulfonic acid, IV stands for a diazotizable aromatic amino,aminohydroxyor amino-azo compound or a substitution product thereof.

3. The process of dyeing leather in full brown shades of even depth withacid azo dyestuffs, which comprises using for the dyeing processdyestuiis formed according to the scheme:

p-nitroaniline+resorcino1--1-amino-8nnphthoi-3.6-di+--axhi he sulionicacid wherein IV stands for a diazotizable aromatic amine, aminohydroxyor amino-azo compound or a substitution product thereof.

4. The process of dyeing leather in full brown shades of even depth withacid azo dyestuiis, which comprises using for the dyeing process a'dyestuii formed according to the scheme:

p-nitroanilineresorcinol1-amino-8-nupthol-3.6--picmmie disulfonic acidacid In testimony whereof, I aflix my signature.

BARTHOLOMAUS VOSSEN.

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